Two outside experts have concluded a Cleveland police officer's fatal shooting of a 12-year-old boy who was carrying a toy gun was a reasonable response to a perceived threat, according to reports released by an Ohio prosecutor's office on Saturday.

The independent conclusions submitted to the Cuyahoga County prosecutor's office come ahead of an expected decision by a grand jury on whether criminal charges are warranted in the November 2014 shooting of Tamir Rice, which was captured on surveillance video.

Cuyahoga County Prosecutor Timothy McGinty said in a statement his office was not reaching any conclusions based on the reports, but an attorney for Rice's family criticized the reports as a "whitewash."

Rice was black while the officer who shot him is white, and the case is one in a series of high-profile deaths of African-Americans at the hands of law enforcement which have raised questions about the use of force by police.

Nearly one year ago, Cleveland police received an emergency call about someone brandishing a gun outside a city recreation center.

Officer Timothy Loehmann shot Rice twice in the abdomen, seconds after his partner who also is white drove their vehicle to within 5 feet (1.5 meters) of the boy. Rice died the next day.

The gun turned out to be an airsoft-type replica pistol that shoots pellets, but had the orange tip removed.

Retired FBI agent Kimberly Crawford, in a review of the shooting, wrote that it was "apparent not only was Officer Loehmann required to make a split-second decision, but also that his response was a reasonable one."

In another report, Colorado prosecutor S. Lamar Sims also concluded that "Officer Loehmann's belief that Rice posed a threat of serious physical harm or death was objectively reasonable, as was his response to that perceived threat."

The reports, which cited federal case law, stood at odds with an opinion from a Cleveland judge who in June found probable cause that Loehmann should face a murder charge. Municipal Court Judge Ronald Adrine's opinion did not compel charges or require the officer's arrest.

McGinty has said the case will go to a grand jury.

"Any presentation to a grand jury — without the prosecutor advocating for Tamir as prosecutors do for crime victims every day — is a charade," Subodh Chandra, an attorney for the Rice family, said in a statement.